HTTP Connector

HTTP Connector allows you to quickly convert HTTP APIs to NDC schema and proxy requests from GraphQL Engine v3 to remote services. The connector can automatically transform OpenAPI 2.0 and 3.0 definitions to NDC schema.

Note

HTTP connector is configuration-based HTTP engine and isn't limited to the OpenAPI specs only. Use OpenAPI Connector if you want to take more control of OpenAPI via code generation.

Features

• No code. Configuration based.
• Composable API collections.
• Supported many API specifications.
• Supported authentication.
• Supported headers forwarding.
• Supported argument presets.
• Supported timeout and retry.
• Supported concurrency and sending distributed requests to multiple servers.

Supported request types

Request Type	Query	Path	Body	Headers
GET	✅	✅	NA	✅
POST	✅	✅	✅	✅
DELETE	✅	✅	✅	✅
PUT	✅	✅	✅	✅
PATCH	✅	✅	✅	✅

Supported content types

Content Type	Supported
application/json	✅
application/xml	✅
application/x-www-form-urlencoded	✅
multipart/form-data	✅
application/octet-stream	✅ (*)
text/*	✅
application/x-ndjson	✅
image/*	✅ (*)

*: Upload file content types are converted to base64 encoding.

Supported authentication

Security scheme	Supported	Comment
API Key	✅
Basic Auth	✅
Bearer Auth	✅
Cookies	✅	Require forwarding the Cookie header from the Hasura engine.
OAuth 2.0	✅	Built-in support for the client_credentials grant. Other grant types require forwarding access tokens from headers by the Hasura engine
mTLS	✅

Quick start

Start the connector server at http://localhost:8080 using the JSON Placeholder APIs.

go run ./server serve --configuration ./connector/testdata/jsonplaceholder

Documentation

• NDC HTTP schema
• Authentication
• Argument Presets
• Distributed Execution
• Recipes: You can find or request pre-built configuration recipes of popular API services here.

Configuration

The connector reads config.{json,yaml} file in the configuration folder. The file contains information about the schema file path and its specification:

files:
  - file: swagger.json
    spec: openapi2
  - file: openapi.yaml
    spec: openapi3
    trimPrefix: /v1
    envPrefix: PET_STORE
  - file: schema.json
    spec: ndc

The config of each element follows the config schema of ndc-http-schema.

You can add many API documentation files into the same connector.

Important

Conflicted object and scalar types will be ignored. Only the type of the first file is kept in the schema.

Supported specs

OpenAPI

HTTP connector supports both OpenAPI 2 and 3 specifications.

• oas3/openapi3: OpenAPI 3.0/3.1.
• oas2/openapi2: OpenAPI 2.0.

HTTP Connector schema

Enum: ndc

HTTP schema is the native configuration schema which other specs will be converted to behind the scene. The schema extends the NDC Specification with HTTP configuration and can be converted from other specs by the NDC HTTP schema CLI.

Timeout and retry

The global timeout and retry strategy can be configured in each file:

files:
  - file: swagger.json
    spec: oas2
    timeout:
      value: 30
    retry:
      times:
        value: 1
      delay:
        # delay between each retry in milliseconds
        value: 500
      httpStatus: [429, 500, 502, 503]

JSON Patch

You can add JSON patches to extend API documentation files. HTTP connector supports merge and json6902 strategies. JSON patches can be applied before or after the conversion from OpenAPI to HTTP schema configuration. It will be useful if you need to extend or fix some fields in the API documentation such as server URL.

files:
  - file: openapi.yaml
    spec: oas3
    patchBefore:
      - path: patch-before.yaml
        strategy: merge
    patchAfter:
      - path: patch-after.yaml
        strategy: json6902

See the example for more context.

License

HTTP Connector is available under the Apache License 2.0.